Photovoltaic cells are a promising energy harvesting technology. Photovoltaic or solar cells provide a means to convert light and generally abundant sun light to electricity. Photovoltaic cells operate on the general principle where light, which in the physical sense is a flux of photons, excites one or more electrons from its valence band to a conduction band in a semiconductor. These electrons are then harvested and stored in a battery or capacitor, or can be used to drive a load. Prior incremental improvements in photovoltaic cell efficiency came at the expense of exotic materials or manufacture of the device. Unfortunately, the present technology is challenged by its inefficiency and thereby renders fossil energy resources economically attractive.
U.S. patent application No. 2005/0155641, by Fafard et al. and titled Solar Cell with Epitaxially Grown Quantum Dot Material, describes a photovoltaic solar cell comprising a plurality of subcells. While the device utilizes Distributed Bragg Reflectors and mentions the use of reflectivity to change the absorption properties, the patent application fails to describe how this can be accomplished. In addition, the patent application neither describes the use of Distributed Bragg Reflectors to trap and recycle light, nor the use of a quantum gain medium to create resonance and thereby a feedback system.
U.S. patent application No. 2005/0247339, by Barnham et al. and titled Method of Operating a Solar Cell, describes a device for the method of operating a solar cell. The invention requires greater than 30 quantum wells within two pieces of bulk semiconductor and requires highly concentrated sunlight on the order of 30-100 suns. While a DBR is incorporated on the bottom of the cell to reflect unused photons back through the device, the invention fails to disclose a resonating means whereby a photon is recycled. In light of the prior art there is a need for . . . .